In the manufacture of heat exchanger coils, U-shape tubes are often used to form the fluid circuit in the heat exchanger. During the assembly of the heat exchanger, it is usually necessary to stack a plurality of thin, plate-like fins on stacker rods at the stamping press. The stack of fins is then removed from the stacker rods and placed on a lacing table and the U-shaped tubes or hairpins are then manually inserted or laced into the stack of fins. Oftentimes, the outer diameter of the legs of the U-shape tubes would be of varying diameters and/or oval in shape and were not completely straight. This resulted in diminished clearances and difficulty in the lacing of hairpins into fin holes. In many instances, it became difficult to control the degree of connection between the fins and the outer diameter of the U-shape tubes because of the widely varying tube diameters and/or shape of the legs in relation to the internal diameter of the holes punched in the fins.
Accordingly, it is an object of this invention to provide a combination tube straightening and tube bending device which enables the manufacture of a U-shape tube having precisely straight and generally parallel legs to enable hairpins to be conveniently laced into the fin stack.
It is a further object of this invention to provide a combination tube straightening and tube bending device, as aforesaid, wherein a tube sizing device is provided so that the outer periphery of the tube is rendered impeccably round, and the tube is straightened prior to its being bent into a U-shape.
It is a further object of this invention to provide a combination tube straightening and tube bending device, as aforesaid, wherein a plurality of tubes are simultaneously sized to the proper outer diameter, straightened and bent into a U-shape.
It is a further object of this invention to provide a combination tube straightening and tube bending device, as aforesaid, wherein the manufacture of the U-shape tubes occurs automatically with little or no supervision being required by operating personnel after the initial setup of the device.
It is a further object of this invention to provide a combination tube straightening and tube bending device, as aforesaid, wherein the length of the legs of the U-shape tube can be controlled during an initial setup of the device.
It is a further object of this invention to provide a combination tube straightening and tube bending device, as aforesaid, which is of a durable construction, easy to maintain and easy to operate.